In the past, electrical power receiving cables from downhole pumps and the like have extended upwardly through bores in tubing hangers or through cable feed throughs in the tubing hanger to a source of electric power. Such installations have the operational disadvantage that when it is necessary to perform maintenance work on the electrical connection within the tubing hangers, the latter must be lifted upwardly from the well heads in which they are disposed. Lifting of a tubing hanger, together with a tubing string supported therefrom, can only be accomplished by use of an expensive power operated mobile unit. Lifting of the tubing hanger even in relatively shallow wells can cost thousands of dollars.
An example of a well head feed through of the above described type that has been used extensively is disclosed in U.S. Pat. Nos. 3,437,149 entitled: "Cable Feed Through Means and Method for Well Head Construction" which patent issued Apr. 8, 1969 to Edward T. Cuginino. This device has the operational disadvantages previously mentioned. In my patent application Ser. No. 432,300, filed Oct. 1, 1982 entitled: "Electric Power Supplying Well Head Assembly", I disclosed and claimed a side entry assembly for effecting electrical communication through a tubing hanger supported in the well head, and the electric power supply portion of the assembly capable of being removed from the tubing hanger for maintenance purposes without removing the tubing hanger from the well head.
Subsequently in the United States patent application entitled:"Top Entry Electrical Transmission Assembly for Submersible Pumping", I disclosed and claimed a second invention for establishing electrical communication between an above ground source of electric power and a submersible pump, which second invention was removably mounted in a tubing hanger and could be removed for maintenance purposes without removing the tubing hanger from a supporting well head.
In both of my prior electrical connection assemblies, it was possible to uncouple the same for maintenance purposes without terminating the flow of electric power therethrough, and as a result arcing or sparking could take place that would be extremely dangerous if it occurred in a potentially hazardous area in which hydrocarbon fumes were present such as on an off shore platform or island.
A major object of the present invention is to provide a top entry electrical transmission assembly that is removably mountable in a well head supported tubing hanger to supply electric power from a source above ground to a submersible pump, and one that can be removed from the tubing hanger without removing the latter from a supporting well head, but only after the electric supply cable has been disconnected from a switchboard or source of electric power, the electric power supply cable separated from the bonnet, and the bonnet removed from the well head, and by so doing eliminating the possibility of an electric arc being inadvertently formed in a potentially hazardous explosive area.
A major object of the present invention is to provide a top entry electric transmission safety assembly for submersible pumping that is simple and easy to use and that eliminates the possibility of electric arcing and sparking occurring in a hazardous area.
These and other objects and advantages of the invention will become apparent from the following description of the preferred form thereof.